1. Field of the Invention
The present invention relates to a method for producing a honeycomb shaped ceramic having a desired shape such as a curved cross section or a corrugated cross section. A honeycomb shaped ceramic obtained by the present invention is useful as a substrate carrying a catalyst, a filter, or a general construction material.
2. Description of the Prior Art
As a substrate carrying a catalyst, a ceramic having a flat honeycomb structure formed by extrusion molding has been used. The honeycomb shaped ceramic has a large geometric surface area because of its plurality of through holes provided from the upper to the lower surfaces thereof. Accordingly, this ceramic is useful as a substrate carrying a catalyst.
Conventionally, such a ceramic has been produced as follows: First, a heat-resistant inorganic material, an appropriate amount of molding auxiliary and water are mixed together, and the composition obtained is extruded to form a flat honeycomb molding. Then, the honeycomb molding is thoroughly dried, after which it is heated to a proper temperature, sintering the heat resistant -inorganic material, and a flat honeycomb ceramic is obtained.
In the conventional method for producing a honeycomb shaped ceramic, a honeycomb shaped ceramic having a curved or corrugated shapes cannot be obtained. Therefore, the application of the honeycomb shaped ceramic and the construction of an apparatus using the honeycomb shaped ceramic have been limited.
In the above-described method, the composition is extruded to form a honeycomb molding, after which this molding is dried with air. The air-drying may introduce an additional problem of deforming the honeycomb molding. To eliminate this problem, an attempt has been made that an inorganic material with an excellent slipping property is used in the composition and the amount of water to be used is reduced. However, a honeycomb molding prepared from such a composition is also deformed at the time of air-drying, or the occurrence of cracks is found in the inside of the honeycomb molding.